Midlife type 2 diabetes and poor glycaemic control as risk factors for cognitive decline in early old age: a post-hoc analysis of the Whitehall II cohort study

Glymphatic function and its influencing factors in different glucose metabolism states

BACKGROUND

Dysfunction of the glymphatic system in the brain in different stages of altered glucose metabolism and its influencing factors are not well characterized.

AIM

To investigate the function of the glymphatic system and its clinical correlates in patients with different glucose metabolism states, the present study employed diffusion tensor imaging along the perivascular space (DTI-ALPS) index.

METHODS

Sample size was calculated using the pwr package in R software. This cross-sectional study enrolled 22 patients with normal glucose metabolism (NGM), 20 patients with prediabetes, and 22 patients with type 2 diabetes mellitus (T2DM). A 3.0T magnetic resonance imaging was used to evaluate the function of the glymphatic system. The mini-mental state examination (MMSE) was used to assess general cognitive function. The DTI-ALPS index of bilateral basal ganglia and the mean DTI-ALPS index was calculated. Further, the correlation between DTI-ALPS and clinical features was assessed.

RESULTS

The left-side, right-side, and mean DTI-ALPS index in the T2DM group were significantly lower than that in the NGM group. The right-side DTI-ALPS and mean DTI-ALPS index in the T2DM group were significantly lower than those in the prediabetes group. DTI-ALPS index lateralization was not observed. The MMSE score in the T2DM group was significantly lower than that in the NGM and prediabetes group. After controlling for sex, the left-side DTI-ALPS and mean DTI-ALPS index in the prediabetes group were positively correlated with 2-hour postprandial blood glucose level; the left-side DTI-ALPS index was negatively correlated with total cholesterol and low-density lipoprotein level. The right-side DTI-ALPS and mean DTI-ALPS index were negatively correlated with the glycosylated hemoglobin level and waist-to-hip ratio in the prediabetes group. The left-side, right-side, and mean DTI-ALPS index in the T2DM group were positively correlated with height. The left-side and mean DTI-ALPS index in the T2DM group were negatively correlated with high-density lipoprotein levels.

CONCLUSION

Cerebral glymphatic system dysfunction may mainly occur in the T2DM stage. Various clinical variables were found to affect the DTI-ALPS index in different glucose metabolism states. This study enhances our understanding of the pathophysiology of diabetic brain damage and provides some potential biological evidence for its early diagnosis.

Glycemic Control, Cognitive Aging, and Impairment Among Diverse Hispanic/Latino Individuals: Study of Latinos- Investigation of Neurocognitive Aging (Hispanic Community Health Study/Study of Latinos)

OBJECTIVE

Hispanic/Latino individuals in the U.S. have the highest prevalence of undiagnosed and untreated diabetes and are at increased risk for cognitive impairment. In this study, we examine glycemic control in relation to cognitive aging and impairment in a large prospective cohort of middle-aged and older Hispanic/Latino individuals of diverse heritages.

RESEARCH DESIGN AND METHODS

Study of Latinos-Investigation of Neurocognitive Aging (SOL-INCA) is a Hispanic Community Health Study/Study of Latinos (HCHS/SOL) ancillary study. HCHS/SOL is a multisite (Bronx, NY; Chicago, IL; Miami, FL; and San Diego, CA), probability sampled prospective cohort study. SOL-INCA enrolled 6,377 diverse Hispanic/Latino individuals aged 50 years and older (2016-2018). The primary outcomes were cognitive function, 7-year cognitive decline, and mild cognitive impairment (MCI). The primary glycemia exposure variables were measured from fasting blood samples collected at HCHS/SOL visit 1 (2008-2011).

RESULTS

Visit 1 mean age was 56.5 years ± 8.2 SD, and the average glycosylated hemoglobin A1C (HbA1c) was 6.12% (43.5 ± 14.6 mmol/mol). After covariate adjustment, higher HbA1c was associated with accelerated 7-year global (b = -0.045; 95% CI -0.070; -0.021; in z score units) and executive cognitive decline and a higher prevalence of MCI (odds ratio 1.20; 95% CI 1.11; 1.29).

CONCLUSIONS

Elevated HbA1c levels were associated with 7-year executive cognitive decline and increased MCI risk among diverse middle-aged and older Hispanic/Latino individuals. Our findings indicate that poor glycemic control in midlife may pose significant risks for cognitive decline and MCI later in life among Hispanic/Latino individuals of diverse heritages.

Implications of cognitive and daily living capabilities on early type 2 diabetes management: a preliminary case-control study

BACKGROUND

Adherence to the transition from oral agents to insulin injections in Type 2 Diabetes Mellitus therapy varies among patients and is not uniformly successful, leading to suboptimal glycemic control in certain cases. This study aims to investigate the potential correlation between cognitive and daily functional capabilities and glycemic control in middle-aged to older adults (40-74 years old) diagnosed with Type 2 Diabetes Mellitus for less than 10 years, specifically those who have recently transitioned to insulin injections and have lower education levels within the context of a developing country.

METHODS

A case-control study was conducted with 30 poorly controlled diabetes mellitus (PCDM) patients recognized by HbA1c levels > 8% compared to 30 fairly controlled diabetes mellitus (FCDM) patients with HbA1c levels ≤ 8%. Basic Montreal Cognitive Assessment (MoCA-B) score of less than 27 was investigated as the exposure among two groups. Additionally, intra- and inter-battery correlations were assessed among MoCA-B and Instrumental Activities of Daily Living (IADL) domains using Pearson's r.

RESULTS

The primary outcomes showed no crude difference between MoCA-B scores in the two diabetic groups (p-value = 0.82). However, after adjusting for age, education, and IADL scores, cognitive decline in the less-educated younger elderly with high IADL scores demonstrated an unexpected protective effect against PCDM (p-value < 0.0001, OR 95% CI = 0-0.26). In linear regression analysis among MoCA-B and IADL scores, "delayed recall" and "orientation" domains from MoCA-B, and "managing medications" and "using the phone" from IADL were negatively associated with HbA1c levels (p-values of < 0.01, 0.043, 0.015, and 0.023, respectively). Intra- and inter-battery correlations further illustrated a strong association between MoCA-B's "orientation" with IADL's "using the phone" and "managing medications" (p-values < 0.0001).

CONCLUSION

Superior performance in certain cognitive domains is linked to better glycemic control. Still, since assessing cognitive domains may be timely in clinical routine, a potential rapid approach might be taken by assessing patients' instrumental abilities to use cell phone or manage medications. Future studies including a larger sample size and a broader spectrum of psychosocial factors are needed to elaborate on our findings.

Association between new-onset atrial fibrillation and dementia among individuals with type 2 diabetes

AIM

To assess the association between new-onset atrial fibrillation and dementia among patients with type 2 diabetes, a group with a high prevalence of atrial fibrillation.

MATERIALS AND METHODS

This cohort study included 22 989 patients with type 2 diabetes from the UK Biobank. New-onset atrial fibrillation was ascertained from hospital admission records. We used an algorithm officially released by the UK Biobank to identify all-cause dementia, Alzheimer's disease and vascular dementia. The algorithm was developed using multiple sources, including hospital admissions and the death registry. Time-varying Cox regression analyses were performed to investigate the association between new-onset atrial fibrillation and dementia.

RESULTS

A total of 2843 participants developed atrial fibrillation, whereas the remaining 20 146 did not. During the median of 12.3 years of follow-up, 844 all-cause dementia, 342 Alzheimer's disease and 246 vascular dementia cases occurred. Compared with participants without atrial fibrillation, those with atrial fibrillation had higher risks of all-cause dementia (hazard ratio [HR] 2.15, 95% confidence interval [CI] 1.80-2.57), Alzheimer's disease (HR 1.44, 95% CI 1.06-1.96) and vascular dementia (HR 3.11, 95% CI 2.32-4.17).

CONCLUSIONS

New-onset atrial fibrillation was associated with a substantially higher risk of all-cause dementia, Alzheimer's disease and vascular dementia in patients with type 2 diabetes. Our findings highlight the significance of atrial fibrillation management in mitigating the risk of dementia in this demographic.

Alterations in Brain Morphometric Networks and Their Relationship with Memory Dysfunction in Patients with Type 2 Diabetes Mellitus

Cognitive dysfunction, a significant complication of type 2 diabetes mellitus (T2DM), can potentially manifest even from the early stages of the disease. Despite evidence of global brain atrophy and related cognitive dysfunction in early-stage T2DM patients, specific regions vulnerable to these changes have not yet been identified. The study enrolled patients with T2DM of less than five years' duration and without chronic complications (T2DM group, n=100) and demographically similar healthy controls (control group, n=50). High-resolution T1-weighted magnetic resonance imaging data were subjected to independent component analysis to identify structurally significant components indicative of morphometric networks. Within these networks, the groups' gray matter volumes were compared, and distinctions in memory performance were assessed. In the T2DM group, the relationship between changes in gray matter volume within these networks and declines in memory performance was examined. Among the identified morphometric networks, the T2DM group exhibited reduced gray matter volumes in both the precuneus (Bonferroni-corrected p=0.003) and insular-opercular (Bonferroni-corrected p=0.024) networks relative to the control group. Patients with T2DM demonstrated significantly lower memory performance than the control group (p=0.001). In the T2DM group, reductions in gray matter volume in both the precuneus (r=0.316, p=0.001) and insular-opercular (r=0.199, p=0.047) networks were correlated with diminished memory performance. Our findings indicate that structural alterations in the precuneus and insular-opercular networks, along with memory dysfunction, can manifest within the first 5 years following a diagnosis of T2DM.

Untargeted Metabolomic Profiling Reveals Differentially Expressed Serum Metabolites and Pathways in Type 2 Diabetes Patients with and without Cognitive Decline: A Cross-Sectional Study

Diabetes is recognized as a risk factor for cognitive decline, but the underlying mechanisms remain elusive. We aimed to identify the metabolic pathways altered in diabetes-associated cognitive decline (DACD) using untargeted metabolomics. We conducted liquid chromatography-mass spectrometry-based untargeted metabolomics to profile serum metabolite levels in 100 patients with type 2 diabetes (T2D) (54 without and 46 with DACD). Multivariate statistical tools were used to identify the differentially expressed metabolites (DEMs), and enrichment and pathways analyses were used to identify the signaling pathways associated with the DEMs. The receiver operating characteristic (ROC) analysis was employed to assess the diagnostic accuracy of a set of metabolites. We identified twenty DEMs, seven up- and thirteen downregulated in the DACD vs. DM group. Chemometric analysis revealed distinct clustering between the two groups. Metabolite set enrichment analysis found significant enrichment in various metabolite sets, including galactose metabolism, arginine and unsaturated fatty acid biosynthesis, citrate cycle, fructose and mannose, alanine, aspartate, and glutamate metabolism. Pathway analysis identified six significantly altered pathways, including arginine and unsaturated fatty acid biosynthesis, and the metabolism of the citrate cycle, alanine, aspartate, glutamate, a-linolenic acid, and glycerophospholipids. Classifier models with AUC-ROC > 90% were developed using individual metabolites or a combination of individual metabolites and metabolite ratios. Our study provides evidence of perturbations in multiple metabolic pathways in patients with DACD. The distinct DEMs identified in this study hold promise as diagnostic biomarkers for DACD patients.

Risk factors for cognitive impairment in middle-aged type 2 diabetic patients: a cross-sectional study

OBJECTIVE

The aim of this study was to investigate risk factors for cognitive impairment (CI) and explore the relationship between obesity and cognition in hospitalised middle-aged patients with type 2 diabetes (T2DM).

METHODS

Subjects were divided into normal cognitive function (NCF) (n=320) and CI (n=204) groups based on the results of the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE). The risk factors for CI were determined by logistic regression analysis and generalised linear modelling. The associations between obesity parameters (body mass index (BMI) and waist circumference (WC)) and cognitive ability were studied with the use of linear regression analysis, piecewise regression modelling and interaction analysis. The receiver operating characteristic curve analysis was used to examine the diagnostic value of influencing factors for cc RESULTS: The prevalence of CI was 38.9% in hospitalised middle-aged T2DM patients (median age, 58 years). Age, WC, hypoglycaemic episode within past 3 months and cerebrovascular disease (CVD) were identified as independent risk factors for CI, while the independent protective factors were education, diabetic dietary pattern, overweight and obesity. BMI was a protective factor for the MoCA score within a certain range, whereas WC was a risk factor for the MMSE and MoCA scores. The area under the curve for the combination of BMI and WC was 0.754 (p<0.001).

CONCLUSION

Age, education, diabetic dietary pattern, WC, overweight, obesity, hypoglycaemic episode in 3 months and CVD may be potential influencing factors for the occurrence of CI in hospitalised middle-aged population with T2DM. The combination of BMI and WC may represent a good predictor for early screening of CI in this population. Nevertheless, more relevant prospective studies are still needed.

Exploring the Interrelationships between Diabetes, Nutrition, Anxiety, and Depression: Implications for Treatment and Prevention Strategies

Across the world, diabetes, depression, and anxiety symptoms have gained widespread recognition as significant public health issues. Recent research has unveiled a mutually influential relationship between diabetes and these two mental health conditions, where each disorder impacts the course and outcomes of the others. The role of nutrition emerges as pivotal in preventing and treating depression, anxiety, and diabetes. A thorough literature review was undertaken to investigate the reciprocal effects between anxiety, depression, and diabetes, including their impact on the development and severity of each condition. Additionally, the effects of nutrition on the prevention and management of depression, anxiety, diabetes, and related complications in at-risk individuals were assessed. Our findings show that mental disorders, such as depression and anxiety, increase the risk of developing type 2 diabetes and are associated with poorer glycemic control, increased diabetes-related complications, and higher mortality rates. Conversely, diabetes is also linked with an increased risk of developing depression and anxiety. The biological, psychological, and social factors that contribute to the comorbidity between these two conditions are complex and multifaceted. Therefore, an integrated approach to the management of both conditions is critical for improving patient outcomes and reducing the overall burden of disease. Nutritional interventions should be utilized to reduce the risk of diabetes in patients with anxiety and depression as well as enhance mental health in patients with diabetes.

Relationship between Cognitive Impairment and Depressive Symptoms with Somatosensory Functions in Diabetic and Non-Diabetic Older Adults and Its Impact on Quality of Life

Aging is an inevitable process that impacts the peripheral and central nervous systems and is considered one of the strongest risk factors for neurodegenerative diseases. In addition, when it also presents with diabetes mellitus, the risk of neurological damage may be further increased. This current study aimed to explore the relationships between peripheral sensory system decline and cognitive functions, the symptoms of depression, and quality of life (QoL) as metrics of central nervous system impairment in institutionalized older adults. A total of 95 individuals participated in this case-control study, which included diabetics and non-diabetics. The superficial sensory pathway was assessed in terms of thermal sensation, nociception, and non-discriminative touch, and the deep sensory pathway was evaluated by assessing vibration and light touch-pressure sensations. To assess function at the intellectual level, the Mini-Mental State Examination (MMSE) and Trail Making Test (TMT) cognitive functional tests were used, while the symptoms of depression and QoL were explored by employing the Yesavage Geriatric Depression Scale and EuroQol 5D questionnaire (EQ-5D), respectively. In the overall population analyses, altered thermal sensation was significantly associated with cognitive impairment (CI; p < 0.05). In turn, bivariate analyses and a binary logistic regression showed that the symptoms of depression and QoL were significantly related to altered vibratory sensation when assessed using a medical tuning fork (p < 0.05). In the group of diabetic patients, those with CI also had significantly lower thermal sensation (p < 0.05) and non-discriminative touch sensation, although this was only a trend (p = 0.055). Diabetics with depression had a significantly worse non-discriminative touch (p < 0.05) and vibratory sensation when tested with a tuning fork (p < 0.05). In addition, poorer QoL was associated with reduced sensitivity to heat (p < 0.05), light touch pressure (p < 0.05), and vibrations when assessed either with a tuning fork (p < 0.05) or a biothesiometer (p < 0.05). In contrast, no relationships were found between sensory functions and cognitive assessments in non-diabetic patients. These findings indicate that superficial sensitivity damage was related to CI, while deep sensation alterations were related to depression and poor QoL, with diabetes apparently further strengthening these relationships.

Relationships Between Body Composition and Cognitive Impairment in Hospitalised Middle-Aged Type 2 Diabetic Patients

Objective

The aim of this study was to elucidate the relationship between specific body composition and the risk of Cognitive Impairment (CI) in middle-aged Type 2 Diabetes Mellitus (T2DM) patients.

Methods

This cross-sectional study included 504 hospitalized patients with T2DM from the Department of Endocrinology and Metabolism of the Tianjin Union Medical Center. Subjects were grouped by sex, and cognitive status was assessed using the Montreal Cognitive Assessment (MoCA). The relationship between body composition and cognitive ability was investigated with the use of linear regression analysis. The association between body composition and CI risk was determined by logistic regression analysis.

Results

The prevalence of CI was 39.3% in middle-aged T2DM patients. After adjusting for age, education, marriage status, carotid atherosclerosis, cerebrovascular disease and hemoglobin, multiple linear regression analysis showed that lean mass index (LMI), body mass index (BMI) and appendicular skeletal muscle index (SMI) were significant predictors for the MoCA scores in men (p < 0.05). In addition, BMI (OR 0.913, 95% CI 0.840-0.992) and LMI (OR 0.820, 95% CI 0.682-0.916) were independent protective factors for CI in males. After adjusted for age, education, marriage status, dietary control of diabetes and cerebrovascular disease, visceral obesity (VO, OR 1.950, 95% CI 1.033-3.684) and abdominal obesity (AO, OR 2.537, 95% CI 1.191-5.403) were risk factors for CI in female patients.

Conclusion

The results suggest that there may be different mechanisms underlying the relationship of body compositions and cognitive performance between middle-aged male and female patients with T2DM. In addition, our finding of potential determinants of cognitive impairment may facilitate the development of intervention programs for middle-aged type 2 diabetic patients. Nevertheless, more large prospective studies looking at cognition and changes in body composition over time are needed in the future to further support their association.

Diabetes and cognitive decline: Challenges and future direction

There is growing evidence that diabetes can induce cognitive decline and dementia. It is a slow, progressive cognitive decline that can occur in any age group, but is seen more frequently in older individuals. Symptoms related to cognitive decline are worsened by chronic metabolic syndrome. Animal models are frequently utilized to elucidate the mechanisms of cognitive decline in diabetes and to assess potential drugs for therapy and prevention. This review addresses the common factors and pathophysiology involved in diabetes-related cognitive decline and outlines the various animal models used to study this condition.

Onset age of diabetes and incident dementia: A prospective cohort study

BACKGROUND

Relationship between age at diagnosis of diabetes and dementia is lacking. The aim of the study was to investigate whether diabetes onset at a younger age was associated with a higher incidence of dementia.

METHODS

466,207 participants free of dementia in the UK biobank (UKB) were included in the analysis. Propensity score matching (PSM) was adopted to match diabetic and non-diabetic participants in different onset age of diabetes groups to evaluate onset age of diabetes and incident dementia.

RESULTS

Compared with non-diabetic participants, diabetes participants had an adjusted hazard ratio (HR) of 1.87 (95 % confidence interval [CI]: 1.73-2.03) for all-cause dementia, 1.85 (95 % CI: 1.60-2.04) for Alzheimer's disease (AD), and 2.86 (95 % CI: 2.47-3.32) for vascular dementia (VD). Among diabetic participants who reported onset age, the adjusted HRs for incident all-cause dementia, AD, and VD were 1.20 (95 % CI: 1.14-1.25), 1.19 (95 % CI: 1.10-1.29), and 1.19 (95 % CI: 1.10-1.28), respectively, per 10 years decrease in age at diabetes onset. After PSM, strength of association between diabetes and all-cause dementia increased with decreasing onset age of diabetes (≥60 years: HR = 1.47, 95 % CI: 1.25-1.74; 45-59 years: HR = 1.66, 95 % CI: 1.40-1.96; <45 years: HR = 2.92, 95 % CI: 2.13-4.01) after multivariable adjustment. Similarly, diabetic participants with onset age <45 years had greatest HRs for incident AD and VD, compared with their matched controls.

LIMITATIONS

Our results only reflect the characteristics of UKB participants.

CONCLUSIONS

Younger age at diabetes onset was significantly associated with a higher risk of dementia in this longitudinal cohort study.

Association of Type 2 Diabetes Mellitus with Cognitive Function in Adults: A Prospective Cohort Study

BACKGROUND

Cognitive role of untreated type 2 diabetes mellitus (T2DM) has been less well substantiated.

OBJECTIVE

We sought to explore the prospective association of T2DM and untreated T2DM with cognitive function among middle-aged and older Chinese adults.

METHODS

Data of 7,230 participants without baseline brain damage, mental retardation, or memory-related diseases in China Health and Retirement Longitudinal Study (CHARLS) from 2011- 2012 to 2015, were analyzed. Fasting plasma glucose and self-reported information on T2DM diagnosis and treatment were assessed. Participants were categorized into normoglycemia, impaired fasting glucose (IFG), and T2DM (including untreated and treated T2DM) groups. Episodic memory and executive function were assessed by modified Telephone Interview for Cognitive Status every two years. We used generalized estimating equation model to examine the association of baseline T2DM status with cognitive function in succeedingyears.

RESULTS

Compared to those with normoglycemia, T2DM was associated with worse overall cognitive function after controlling for demographic variables, lifestyles, follow-up time, major clinical factors, and baseline cognitive function, although the associations were statistically non-significant (β= -0.19, 95% CI: -0.39, 0.00). However, a significant association was mainly observed for those with untreated T2DM (β= -0.26, 95% CI: -0.47, -0.04), especially in the domain of executive function (β= -0.19, 95% CI: -0.35, -0.03). In general, IFG and treated T2DM individuals had similar levels of cognitive function with normoglycemia participants.

CONCLUSION

Our findings supported a detrimental role of untreated T2DM on cognitive function among middle-aged and older adults. Screening and early treatment for T2DM are warranted for maintaining better cognitive function in later life.

Associations of baseline glycemic status and its transitions with cognitive and physical functioning decline

OBJECTIVE

Evidence about the decline of cognition and physical function across glycemic status (normoglycemia, prediabetes, and diabetes) is inconsistent. We evaluated longitudinal changes in cognition and physical function according to glycemic status and also different glycemic transitions.

STUDY DESIGN

Population-based cohort study.

METHODS

9307 participants (mean age 59.7 years, 53.7 % women) were included from the China Health and Retirement Longitudinal Study (2011-2018). Global cognition (assessed by orientation, memory, and executive function) and physical function (calculated as the sum of impaired basic and instrumental activities of daily living) were assessed in each wave. The glycemic status was assessed in waves 2011 and 2015. Diabetes was defined as fasting blood glucose ≥7.0 mmol/L, HbA1c ≥6.5 %, self-reported diabetes, or glucose-lowering medication use. Prediabetes was defined as fasting blood glucose 5.6-6.9 mmol/L or an HbA1c of 5.7-6.4 %.

RESULTS

Compared with normoglycemia, baseline diabetes was associated with a faster decline in orientation (-0.018 SD/year, 95%CI -0.032, -0.004) and a faster increase in physical function score (0.082 /year, 95%CI 0.038, 0.126). We did not observe any effect of prediabetes on the changing rate of cognition and physical function. Progression from normoglycemia to diabetes between waves 2011 and 2015 was associated with a significantly faster decline in global cognition, memory, executive function, and physical function compared with stable normoglycemia.

CONCLUSIONS

Baseline diabetes was associated with accelerated decline of cognition and physical function. Associations with prediabetes were not observed, suggesting an important short diagnostic window when diabetes presents de novo.

Neurotransmitters in Type 2 Diabetes and the Control of Systemic and Central Energy Balance

Efficient signal transduction is important in maintaining the function of the nervous system across tissues. An intact neurotransmission process can regulate energy balance through proper communication between neurons and peripheral organs. This ensures that the right neural circuits are activated in the brain to modulate cellular energy homeostasis and systemic metabolic function. Alterations in neurotransmitters secretion can lead to imbalances in appetite, glucose metabolism, sleep, and thermogenesis. Dysregulation in dietary intake is also associated with disruption in neurotransmission and can trigger the onset of type 2 diabetes (T2D) and obesity. In this review, we highlight the various roles of neurotransmitters in regulating energy balance at the systemic level and in the central nervous system. We also address the link between neurotransmission imbalance and the development of T2D as well as perspectives across the fields of neuroscience and metabolism research.

The factors associated with cognitive function among community-dwelling older adults in Taiwan

BACKGROUND

This research aimed to investigate the associations of anthropometric measurements, physiological parameters, chronic disease comorbidities, and social and lifestyle factors with cognitive function amongst community-dwelling older adults in Taiwan.

METHODS

This was an observational, cross-sectional study involving 4,578 participants at least 65 years old, recruited between January 2008 and December 2018 from the Annual Geriatric Health Examinations Program. Cognitive function was assessed using the short portable mental state questionnaire (SPMSQ). Multivariable logistic regression was done to analyze the factors associated with cognitive impairment.

RESULTS

Among the 4,578 participants, 103 people (2.3%) with cognitive impairment were identified. Associated factors were age (odds ratio (OR) = 1.16, 95% confidence interval (CI) = 1.13,1.20), male gender (OR = 0.39, 95% CI = 0.21,0.72), diabetes mellitus (DM) (OR = 1.70, 95% CI = 1.03, 2.82), hyperlipidemia (OR = 0.47, 95% CI = 0.25, 0.89), exercise (OR = 0.44, 95% CI = 0.34, 0.56), albumin (OR = 0.37, 95% CI = 0.15, 0.88), and high-density lipoprotein (HDL) (OR = 0.98, 95% CI = 0.97, 1.00). Whereas waistline, alcohol intake in recent six months, and hemoglobin was not significantly associated with cognitive impairment (all p > 0.05).

CONCLUSIONS

Our findings suggested that people with older age and a history of DM had a higher risk of cognitive impairment. Male gender, a history of hyperlipidemia, exercise, a high albumin level, and a high HDL level seemed to be associated with a lower risk of cognitive impairment amongst older adults.

Food Insecurity and Cognitive Trajectories in Community-Dwelling Medicare Beneficiaries 65 Years and Older

Importance

Food insecurity has a known association with prevalent impaired cognition. However, it is unknown whether food insecurity has a longitudinal association with cognitive decline among older adults.

Objective

To determine whether food insecurity is associated with a faster decline in cognitive function among community-dwelling older adults.

Design, Setting, and Participants

This retrospective cohort study used data from a nationally representative sample of Medicare beneficiaries 65 years and older recruited for the National Health and Aging Trends Study (NHATS). Community-dwelling NHATS participants were followed up for a maximum of 7 years (mean [SD] follow-up duration, 5.4 [1.1] years). Data were collected from January 1, 2012, to December 31, 2020, and analyzed from December 23, 2021, to December 6, 2022.

Exposures

Self-reported food insecurity assessed from 2012 to 2019.

Main Outcomes and Measures

Primary outcomes were immediate memory, delayed memory, and executive function collected from 2013 to 2020. Immediate and delayed recall were assessed by a 10-item word-list memory task (range, 0-10, with higher scores indicating more words recalled). Executive function was measured by the clock drawing test (range, 0-5, with higher scores indicating more accurate depiction of a clock). Each year's cognitive functions were linked to the prior year's food insecurity data. Linear mixed-effects models with random slopes and intercepts were used to examine the association between food insecurity and cognitive decline. Analytic weights in each year were applied to represent community-dwelling Medicare beneficiaries 65 years and older in 2011.

Results

Of 3037 participants, a weighted 57.8% (raw count, 1345) were younger than 75 years, 56.2% (raw count, 1777) were women, and most (84.9% [raw count, 2268]) were White. Over 7 years, 417 (weighted proportion, 12.1%) experienced food insecurity at least once. Food insecurity was associated with a faster decline in executive function in a fully adjusted model: the mean difference of annual change in executive function score between people exposed to and not exposed to food insecurity was -0.04 (95% CI, -0.09 to -0.003) points. However, food insecurity was not associated with changes in immediate and delayed memory (0.01 [95% CI, -0.05 to 0.08] and -0.01 [95% CI, -0.08 to 0.06], respectively).

Conclusions and Relevance

Among community-dwelling older adults, food insecurity was prevalent and associated with a decline in executive function. Interventions and policies aiming to increase healthy food access or reduce food insecurity should be assessed for their impact on older adults' cognitive outcome.

How Can Insulin Resistance Cause Alzheimer's Disease?

Alzheimer's disease (AD) is a neurodegenerative disorder associated with cognitive decline. Despite worldwide efforts to find a cure, no proper treatment has been developed yet, and the only effective countermeasure is to prevent the disease progression by early diagnosis. The reason why new drug candidates fail to show therapeutic effects in clinical studies may be due to misunderstanding the cause of AD. Regarding the cause of AD, the most widely known is the amyloid cascade hypothesis, in which the deposition of amyloid beta and hyperphosphorylated tau is the cause. However, many new hypotheses were suggested. Among them, based on preclinical and clinical evidence supporting a connection between AD and diabetes, insulin resistance has been pointed out as an important factor in the development of AD. Therefore, by reviewing the pathophysiological background of brain metabolic insufficiency and insulin insufficiency leading to AD pathology, we will discuss how can insulin resistance cause AD.

Depressive symptoms mediate the longitudinal association between diabetes and subjective cognitive decline. Findings from a semirural multi-ethnic older population in Malaysia

The potential role of psychological distress as the pathway linking diabetes and subjective cognitive decline (SCD) is still unclear. This study aims to investigate whether depressive symptoms mediate the relationship between diabetes and SCD in older adults. Baseline data from 3428 adults (55-94 years) of the South East Asia Community Observatory (SEACO), Malaysia were utilized. Subjective cognitive complaints (SCC) were recorded at baseline and five years later. Mediation analyses with non-parametric bootstrapping methods were employed. A proportion of 20% of participants without SCC at baseline reported a decline in SCC after 5 years of follow-up. Known diabetes (β = -0.13, SE = 0.05, p = 0.02) and depressive symptoms (ß = -0.18, SE = 0.05, p = 0.001) were independently associated with SCD. Previously diagnosed diabetes was associated with depressive symptoms at baseline (ß = 0.04, SE = 0.02, p = 0.01), and greater SCD at follow-up (β = -0.19, SE = 0.06, p = 0.001). Mediation analyses revealed that 9% of the association between diabetes and SCD was attributable to an indirect effect through depressive symptoms (ß = -0.01, 95% CI 0.02-0.001, p < 0.0001). This study provides further evidence of the detrimental effects of diabetes and depression on subjective cognitive decline. Our findings also suggest that depression is an important pathway linking previously diagnosed diabetes with subjective cognitive decline in older adulthood.

MRI-based machine learning model: A potential modality for predicting cognitive dysfunction in patients with type 2 diabetes mellitus

Background: Type 2 diabetes mellitus (T2DM) is a crucial risk factor for cognitive impairment. Accurate assessment of patients' cognitive function and early intervention is helpful to improve patient's quality of life. At present, neuropsychiatric screening tests is often used to perform this task in clinical practice. However, it may have poor repeatability. Moreover, several studies revealed that machine learning (ML) models can effectively assess cognitive impairment in Alzheimer's disease (AD) patients. We investigated whether we could develop an MRI-based ML model to evaluate the cognitive state of patients with T2DM. Objective: To propose MRI-based ML models and assess their performance to predict cognitive dysfunction in patients with type 2 diabetes mellitus (T2DM). Methods: Fluid Attenuated Inversion Recovery (FLAIR) of magnetic resonance images (MRI) were derived from 122 patients with T2DM. Cognitive function was assessed using the Chinese version of the Montréal Cognitive Assessment Scale-B (MoCA-B). Patients with T2DM were separated into the Dementia (DM) group (n = 40), MCI group (n = 52), and normal cognitive state (N) group (n = 30), according to the MoCA scores. Radiomics features were extracted from MR images with the Radcloud platform. The variance threshold, SelectKBest, and least absolute shrinkage and selection operator (LASSO) were used for the feature selection. Based on the selected features, the ML models were constructed with three classifiers, k-NearestNeighbor (KNN), Support Vector Machine (SVM), and Logistic Regression (LR), and the validation method was used to improve the effectiveness of the model. The area under the receiver operating characteristic curve (ROC) determined the appearance of the classification. The optimal classifier was determined by the principle of maximizing the Youden index. Results: 1,409 features were extracted and reduced to 13 features as the optimal discriminators to build the radiomics model. In the validation set, ROC curves revealed that the LR classifier had the best predictive performance, with an area under the curve (AUC) of 0.831 in DM, 0.883 in MIC, and 0.904 in the N group, compared with the SVM and KNN classifiers. Conclusion: MRI-based ML models have the potential to predict cognitive dysfunction in patients with T2DM. Compared with the SVM and KNN, the LR algorithm showed the best performance.

Alzheimer’s Disease Polygenic Risk Score Is Not Associated With Cognitive Decline Among Older Adults With Type 2 Diabetes

Objectives

Multiple risk loci for late-onset Alzheimer’s disease (LOAD) have been identified. Type 2 diabetes (T2D) is a risk factor for cognitive decline, dementia and Alzheimer’s disease (AD). We investigated the association of polygenic risk score (PRS) for LOAD with overall cognitive functioning and longitudinal decline, among older adults with T2D.

Methods

The study included 1046 Jewish participants from the Israel Diabetes and Cognitive Decline (IDCD) study, aged ≥ 65 years, diagnosed with T2D, and cognitively normal at baseline. The PRS included variants from 26 LOAD associated loci (at genome-wide significance level), and was calculated with and without APOE. Outcome measures, assessed in 18 months intervals, were global cognition and the specific domains of episodic memory, attention/working memory, executive functions, and language/semantic categorization. Random coefficient models were used for analysis, adjusting for demographic variables, T2D-related characteristics, and cardiovascular factors. Additionally, in a subsample of 202 individuals, we analyzed the association of PRS with the volumes of total gray matter, frontal lobe, hippocampus, amygdala, and white matter hyperintensities. Last, the association of PRS with amyloid beta (Aβ) burden was examined in 44 participants who underwent an 18F-flutemetamol PET scan.

Results

The PRS was not significantly associated with overall functioning or decline in global cognition or any of the specific cognitive domains. Similarly, following correction for multiple testing, there was no association with Aβ burden and other brain imaging phenotypes.

Conclusion

Our results suggest that the cumulative effect of LOAD susceptibility loci is not associated with a greater rate of cognitive decline in older adults with T2D, and other pathways may underlie this link.

Gait Characteristics and Cognitive Function in Middle-Aged Adults with and without Type 2 Diabetes Mellitus: Data from ENBIND

Type 2 Diabetes Mellitus (T2DM) in midlife is associated with a greater risk of dementia in later life. Both gait speed and spatiotemporal gait characteristics have been associated with later cognitive decline in community-dwelling older adults. Thus, the assessment of gait characteristics in uncomplicated midlife T2DM may be important in selecting-out those with T2DM at greatest risk of later cognitive decline. We assessed the relationship between Inertial Motion Unit (IMUs)-derived gait characteristics and cognitive function assessed via Montreal Cognitive Assessment (MoCA)/detailed neuropsychological assessment battery (CANTAB) in middle-aged adults with and without uncomplicated T2DM using both multivariate linear regression and a neural network approach. Gait was assessed under (i) normal walking, (ii) fast (maximal) walking and (iii) cognitive dual-task walking (reciting alternate letters of the alphabet) conditions. Overall, 138 individuals were recruited (n = 94 with T2DM; 53% female, 52.8 ± 8.3 years; n = 44 healthy controls, 43% female, 51.9 ± 8.1 years). Midlife T2DM was associated with significantly slower gait velocity on both slow and fast walks (both p < 0.01) in addition to a longer stride time and greater gait complexity during normal walk (both p < 0.05). Findings persisted following covariate adjustment. In analyzing cognitive performance, the strongest association was observed between gait velocity and global cognitive function (MoCA). Significant associations were also observed between immediate/delayed memory performance and gait velocity. Analysis using a neural network approach did not outperform multivariate linear regression in predicting cognitive function (MoCA) from gait velocity. Our study demonstrates the impact of uncomplicated T2DM on gait speed and gait characteristics in midlife, in addition to the striking relationship between gait characteristics and global cognitive function/memory performance in midlife. Further studies are needed to evaluate the longitudinal relationship between midlife gait characteristics and later cognitive decline, which may aid in selecting-out those with T2DM at greatest-risk for preventative interventions.

Depressive symptoms mediate the relationship between diabetes and cognitive performance in a community-based sample of older adults

AIMS

To evaluate whether diabetes and prediabetes are associated with impaired cognitive performance among older adults and examine depressive symptoms as a mediator.

METHODS

We used cross-sectional data from the Einstein Aging Study, a systematically recruited, community-based cohort study of diverse older adults (N = 794; Age Mean (SD) = 78.9 (5.3); 64.4% Non-Hispanic White, 28.7% Non-Hispanic Black, 5.7% Hispanic). Diabetes status was established via self-reported diagnosis, prescribed medications, and fasting blood glucose. Depressive symptoms were assessed using the Geriatric Depression Scale. Cognitive tests included Digit Symbol, Trails-B, Free Recall, Category Fluency, Boston Naming, and Block Design. Linear regression and mediation analyses were applied.

RESULTS

Compared to those without diabetes, diabetes was associated with worse performance on all cognitive tests (ps < 0.05), except Trails-B (p = 0.53), and increased depressive symptoms (p < 0.01). For diabetes, mediation via increased depressive symptoms was observed for Free Recall (p = 0.044), Category Fluency (p = 0.033), and Boston Naming (p = 0.048).

CONCLUSIONS

Diabetes was consistently associated with worse cognitive performance and increased depressive symptoms among this older cohort, while prediabetes was not. Mediation findings suggest depressive symptoms may be a biobehavioral pathway linking diabetes and cognition, though the temporal sequence is unclear. If causal, addressing both diabetes and depressive symptoms among older adults may protect cognitive function.

Association Between Diabetes and Gray Matter Atrophy Patterns in a General Older Japanese Population: The Hisayama Study

OBJECTIVE

To examine the association between diabetes and gray matter atrophy patterns in a general older Japanese population.

RESEARCH DESIGN AND METHODS

In 2012, a total of 1,189 community-dwelling Japanese aged ≥65 years underwent brain MRI scans. Regional gray matter volumes (GMV) and intracranial volume (ICV) were measured by applying voxel-based morphometry (VBM) methods. The associations of diabetes and related parameters with the regional GMV/ICV were examined using an ANCOVA. The regional gray matter atrophy patterns in the subjects with diabetes or elevated fasting plasma glucose (FPG) or 2-h postload glucose (2hPG) levels were investigated using VBM.

RESULTS

Subjects with diabetes had significantly lower mean values of GMV/ICV in the frontal lobe, temporal lobe, insula, deep gray matter structures, and cerebellum than subjects without diabetes after adjusting for potential confounders. A longer duration of diabetes was also significantly associated with lower mean values of GMV/ICV in these brain regions. The multivariable-adjusted mean values of the temporal, insular, and deep GMV/ICV decreased significantly with elevating 2hPG levels, whereas higher FPG levels were not significantly associated with GMV/ICV of any brain regions. In the VBM analysis, diabetes was associated with gray matter atrophy in the bilateral superior temporal gyri, right middle temporal gyrus, left inferior temporal gyrus, right middle frontal gyrus, bilateral thalami, right caudate, and right cerebellum.

CONCLUSIONS

The current study suggests that a longer duration of diabetes and elevated 2hPG levels are significant risk factors for gray matter atrophy in various brain regions.

Dairy Product Consumption and Changes in Cognitive Performance: Two-Year Analysis of the PREDIMED-Plus Cohort

SCOPE

Dairy consumption has been suggested to impact cognition; however, evidence is limited and inconsistent. This study aims to longitudinally assess the association between dairy consumption with cognitive changes in an older Spanish population at high cardiovascular disease risk.

METHODS AND RESULTS

Four thousand six hundred sixty eight participants aged 55-75 years, completed a validated food frequency questionnaire at baseline and a neuropsychological battery of tests at baseline and 2-year follow-up. Multivariable linear regression models are used, scaled by 100 (i.e., the units of β correspond to 1 SD/100), to assess associations between baseline tertile daily consumption and 2-year changes in cognitive performance. Participants in the highest tertile of total milk and whole-fat milk consumption have a greater decline in global cognitive function (β: -4.71, 95% CI: -8.74 to -0.69, p-trend = 0.020 and β: -6.64, 95% CI: -10.81 to -2.47, p-trend = 0.002, respectively) compared to those in the lowest tertile. No associations are observed between low fat milk, yogurt, cheese or fermented dairy consumption, and changes in cognitive performance.

CONCLUSION

Results suggest there are no clear prospective associations between consumption of most commonly consumed dairy products and cognition, although there may be an association with a greater rate of cognitive decline over a 2-year period in older adults at high cardiovascular disease risk for whole-fat milk.

Cognitive disorder and dementia in type 2 diabetes mellitus

Insulin, a key pleiotropic hormone, regulates metabolism through several signaling pathways in target tissues including skeletal muscle, liver, and brain. In the brain, insulin modulates learning and memory, and impaired insulin signaling is associated with metabolic dysregulation and neurodegenerative diseases. At the receptor level, in aging and Alzheimer’s disease (AD) models, the amount of insulin receptors and their functions are decreased. Clinical and animal model studies suggest that memory improvements are due to changes in insulin levels. Furthermore, diabetes mellitus (DM) and insulin resistance are associated with age-related cognitive decline, increased levels of β-amyloid peptide, phosphorylation of tau protein; oxidative stress, pro-inflammatory cytokine production, and dyslipidemia. Recent evidence shows that deleting brain insulin receptors leads to mild obesity and insulin resistance without influencing brain size and apoptosis development. Conversely, deleting insulin-like growth factor 1 receptor (IGF-1R) affects brain size and development, and contributes to behavior changes. Insulin is synthesized locally in the brain and is released from the neurons. Here, we reviewed proposed pathophysiological hypotheses to explain increased risk of dementia in the presence of DM. Regardless of the exact sequence of events leading to neurodegeneration, there is strong evidence that mitochondrial dysfunction plays a key role in AD and DM. A triple transgenic mouse model of AD showed mitochondrial dysfunction, oxidative stress, and loss of synaptic integrity. These alterations are comparable to those induced in wild-type mice treated with sucrose, which is consistent with the proposal that mitochondrial alterations are associated with DM and contribute to AD development. Alterations in insulin/IGF-1 signaling in DM could lead to mitochondrial dysfunction and low antioxidant capacity of the cell. Thus, insulin/IGF-1 signaling is important for increased neural processing and systemic metabolism, and could be a specific target for therapeutic strategies to decrease alterations associated with age-related cognitive decline.

Occurrence of mild cognitive impairment with hyperinsulinaemia in Africans with advanced type 2 diabetes mellitus

There is paucity of information on the prevalence of mild cognitive impairment (MCI) among individuals with type 2 diabetes mellitus (T2DM) in sub-Saharan Africa, including Nigeria. In addition, the role of hyperinsulinaemia in the development of MCI needs further investigation. This study sought to assess cognition and hyperinsulinaemia, with the associated characteristics in patients with advanced T2DM. Cognition was assessed using Montreal cognitive assessment test (MoCA), while fasting plasma insulin was measured using an ELISA kit. Sixty one diabetic subjects and 32 non-diabetic controls, matched for age, gender and level of education were studied. The diabetics had MCI while the controls had normal cognitive function. About 88.5% of the diabetic subjects had MCI, in contrast with only 50% of the non-diabetic controls. The most significantly affected cognitive domains among the diabetics were executive function, naming, attention, abstraction and delayed recall. Among the diabetics, MCI correlated with age, weight and body mass index (BMI); and in addition, age and weight found to be significant predictors of MCI. Plasma insulin concentration among the diabetics (16.24 ± 13.5 µIU/ml) was more than twice that of the controls (7.59 ± 2.9 µIU/ml). Hyperinsulinaemia among the diabetics correlated with weight, BMI, blood pressure and fasting blood sugar (FBS). Glycated haemoglobin and FBS levels were higher among diabetics compared with the controls. In conclusion, Africans with advanced T2DM show multi-domain MCI with high prevalence, coexisting with hyperinsulinaemia. Majority of the patients have diabetic complications and poor glycaemic control. Hyperinsulinaemia may play a complementary role in the pathophysiology of MCI in T2DM.

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Patients with advanced T2DM manifest multi-domain MCI with up to 88% prevalence.

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There is hyperinsulinaemia coexisting with the MCI among patients with advanced 2DM.

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Majority of the patients have diabetic complications and poor glycaemic control.

Altered Structural and Functional MRI Connectivity in Type 2 Diabetes Mellitus Related Cognitive Impairment: A Review

Type 2 diabetes mellitus (T2DM) is associated with cognitive impairment in many domains. There are several pieces of evidence that changes in neuronal neuropathies and metabolism have been observed in T2DM. Structural and functional MRI shows that abnormal connections and synchronization occur in T2DM brain circuits and related networks. Neuroplasticity and energy metabolism appear to be principal effector systems, which may be related to amyloid beta (Aβ) deposition, although there is no unified explanation that includes the complex etiology of T2DM with cognitive impairment. Herein, we assume that cognitive impairment in diabetes may lead to abnormalities in neuroplasticity and energy metabolism in the brain, and those reflected to MRI structural connectivity and functional connectivity, respectively.

Diabetes Treatment Is Associated With Better Cognitive Function: The Age Disparity

Background: Diabetes mellitus (DM) is a recognised risk factor for cognitive dysfunction. The purpose of this study was to explore the relationship between active treatment for DM and cognitive function in middle-aged (< 60 years) and older adults (≥60 years), respectively.

Methods: A total of 13,691 participants (58.55 ± 9.64 years, 47.40% of men) from the Chinese Health and Retirement Longitudinal Study (CHARLS) were included. The participants were classified into three groups according to whether or not they have diabetes and to their diabetes treatment status: diabetes-free, treated-diabetes and untreated-diabetes, in which the diabetes-free group was regarded as reference specially. Cognitive function was assessed by two interview-based measurements for mental intactness and episodic memory.

Results: Compared with the participants in the diabetes-free group, the older participants in the treated-diabetes group had better performance in terms of mental intactness (β = 0.37, 95% CI = 0.04–0.70). No significant association was observed in the middle-aged participants. In the subgroup analyses, the lower cognitive score was only observed in people without depression, who had never smoked and drunk, and with a normal weight (body mass index: 18.5–23.9 kg/m²).

Conclusion: The cognitive function of actively treated diabetic patients was better than that of patients without diabetes, but the improvement was significant only in elderly people. Depression, smoking, drinking, and an abnormal weight may attenuate this effect.

Paradoxical cognitive trajectories in men from earlier to later adulthood

Because longitudinal studies of aging typically lack cognitive data from earlier ages, it is unclear how general cognitive ability (GCA) changes throughout the life course. In 1173 Vietnam Era Twin Study of Aging (VETSA) participants, we assessed young adult GCA at average age 20 and current GCA at 3 VETSA assessments beginning at average age 56. The same GCA index was used throughout. Higher young adult GCA and better GCA maintenance were associated with stronger specific cognitive abilities from age 51 to 73. Given equivalent GCA at age 56, individuals who had higher age 20 GCA outperformed those whose GCA remained stable in terms of memory, executive function, and working memory abilities from age 51 to 73. Thus, paradoxically, despite poorer maintenance of GCA, high young adult GCA still conferred benefits. Advanced predicted brain age and the combination of elevated vascular burden and APOE-ε4 status were associated with poorer maintenance of GCA. These findings highlight the importance of distinguishing between peak and current GCA for greater understanding of cognitive aging.

Trends in leading causes of hospitalisation of adults with diabetes in England from 2003 to 2018: an epidemiological analysis of linked primary care records

BACKGROUND

Diabetes leads to a wide range of established vascular and metabolic complications that has resulted in the implementation of diverse prevention programmes across high-income countries. Diabetes has also been associated with an increased risk of a broader set of conditions including cancers, liver disease, and common infections. We aimed to examine the trends in a broad set of cause-specific hospitalisations in individuals with diabetes in England from 2003 to 2018.

METHODS

In this epidemiological analysis, we identified 309 874 individuals 18 years or older with diabetes (type 1 or 2) in England from the Clinical Practice Research Datalink linked to Hospital Episode Statistics inpatient data from 2003 to 2018. We generated a mixed prevalent and incident diabetes study population through serial cross sections and follow-up over time. We used a discretised Poisson regression model to estimate annual cause-specific hospitalisation rates in men and women with diabetes across 17 cause groupings. We generated a 1:1 age-matched and sex-matched population of individuals without diabetes to compare cause-specific hospitalisation rates in those with and without diabetes.

FINDINGS

Hospitalisation rates were higher for all causes in persons with diabetes than in those without diabetes throughout the study period. Diabetes itself and ischaemic heart disease were the leading causes of excess (defined as absolute difference in the rate in the populations with and without diabetes) hospitalisation in 2003. By 2018, non-infectious and non-cancerous respiratory conditions, non-diabetes-related cancers, and ischaemic heart disease were the most common causes of excess hospitalisation across men and women. Hospitalisation rates of people with diabetes declined and causes of hospitalisation changed. Almost all traditional diabetes complication groups (vascular diseases, amputations, and diabetes) decreased, while conditions non-specific to diabetes (cancers, infections, non-infectious and non-cancerous respiratory conditions) increased. These differing trends represented a change in the cause of hospitalisation, such that the traditional diabetes complications accounted for more than 50% of hospitalisation in 2003, but only approximately 30% in 2018. In contrast, the proportion of hospitalisations due to respiratory infections between the same time period increased from 3% to 10% in men and from 4% to 12% in women.

INTERPRETATIONS

Changes in the composition of excess risk and hospitalisation burden in those with diabetes means that preventative and clinical measures should evolve to reflect the diverse set of causes that are driving persistent excess hospitalisation in those with diabetes.

FUNDING

Wellcome Trust.

Risk of Incident Dementia According to Glycemic Status and Comorbidities of Hyperglycemia: A Nationwide Population-Based Cohort Study

OBJECTIVE

To investigate the risk of incident dementia according to fasting glucose levels and presence of comorbidities.

RESEARCH DESIGN AND METHODS

Using a health insurance claims database and the results of biennial health examinations in South Korea, we selected 8,400,950 subjects aged ≥40 years who underwent health examinations in 2009-2010. We followed them until 2016. Subjects' baseline characteristics were categorized by presence of diabetes (yes/no) and glycemic status as normoglycemia, impaired fasting glucose (IFG), new-onset diabetes, or known diabetes (duration <5 years or ≥5 years). We estimated adjusted hazard ratios (aHRs) for dementia occurrence in each category.

RESULTS

During the observation period of 48,323,729 person-years, all-cause dementia developed in 353,392 subjects (4.2%). Compared with normoglycemia, aHRs (95% CI) were 1.01 (1.01-1.02) in IFG, 1.45 (1.44-1.47) in new-onset diabetes, 1.32 (1.30-1.33) in known diabetes <5 years, and 1.62 (1.60-1.64) in known diabetes ≥5 years. We found that associations between ischemic heart disease and chronic kidney disease with incident dementia were affected by the presence of diabetes. Ischemic stroke showed a greater association with incident dementia than diabetes.

CONCLUSIONS

Mild degrees of hyperglycemia and presence of comorbidities were associated with incident dementia. Intervention during the prodromal stage of a chronic disease (e.g., prediabetes) could be considered for dementia prevention.

Vascular Cognitive Impairment (VCI)

Vascular cognitive impairment (VCI) is predominately caused by vascular risk factors and cerebrovascular disease. VCI includes a broad spectrum of cognitive disorders, from mild cognitive impairment to vascular dementia caused by ischemic or hemorrhagic stroke, and vascular factors alone or in a combination with neurodegeneration including Alzheimer's disease (AD) and AD-related dementia. VCI accounts for at least 20-40% of all dementia diagnosis. Growing evidence indicates that cerebrovascular pathology is the most important contributor to dementia, with additive or synergistic interactions with neurodegenerative pathology. The most common underlying mechanism of VCI is chronic age-related dysregulation of CBF, although other factors such as inflammation and cardiovascular dysfunction play a role. Vascular risk factors are prevalent in VCI and if measured in midlife they predict cognitive impairment and dementia in later life. Particularly, hypertension, high cholesterol, diabetes, and smoking at midlife are each associated with a 20 to 40% increased risk of dementia. Control of these risk factors including multimodality strategies with an inclusion of lifestyle modification is the most promising strategy for treatment and prevention of VCI. In this review, we present recent developments in age-related VCI, its mechanisms, diagnostic criteria, neuroimaging correlates, vascular risk determinants, and current intervention strategies for prevention and treatment of VCI. We have also summarized the most recent and relevant literature in the field of VCI.

Diabetes Mellitus, Elevated Hemoglobin A1c, and Glycated Albumin Are Associated with the Presence of All-Cause Dementia and Alzheimer's Disease: The JPSC-AD Study

BACKGROUND

Glucose dysmetabolism is an important risk factor for dementia.

OBJECTIVE

We investigated the associations of diabetes mellitus, the levels of glycemic measures, and insulin resistance and secretion measures with dementia and its subtypes in a cross-sectional study.

METHODS

In this study, 10,214 community-dwelling participants were enrolled. Hemoglobin A1c (HbA1c), the homeostasis model assessment (HOMA) for insulin resistance (HOMA-IR), the HOMA of percent β-cell function (HOMA-β), and the glycated albumin (GA) was evaluated. The associations of each measure with Alzheimer's disease (AD) and vascular dementia (VaD) were investigated.

RESULTS

The multivariable-adjusted odds ratios (ORs) of AD were significantly higher in participants with diabetes mellitus than in those without diabetes (1.46 [95% CI: 1.08-1.97]). Higher HbA1c levels were significantly associated with AD at diabetes (≥6.5%) and even at prediabetes (5.7 %-6.4 %) levels; multivariable-adjusted ORs for AD in participants at the diabetes level were 1.72 (95% CI: 1.19-2.49), and those in participants at the prediabetes level were 1.30 (95% CI: 1.00-1.68), compared with those in normal participants. Moreover, higher GA levels were associated with AD. No associations were observed between the diabetic status or the levels of glycemic measures and VaD. In addition, no significant relationships were observed between insulin resistance and secretion measurements and AD and VaD.

CONCLUSION

Our findings indicate that diabetes mellitus and hyperglycemia are significantly associated with AD, even in individuals at the prediabetes level.

Glycemic Dysregulations Are Associated With Worsening Cognitive Function in Older Participants at High Risk of Cardiovascular Disease: Two-Year Follow-up in the PREDIMED-Plus Study

Introduction

Type 2 diabetes has been linked to greater cognitive decline, but other glycemic parameters such as prediabetes, diabetes control and treatment, and HOMA-IR and HbA1c diabetes-related biomarkers have shown inconsistent results. Furthermore, there is limited research assessing these relationships in short-term studies. Thus, we aimed to examine 2-year associations between baseline diabetes/glycemic status and changes in cognitive function in older participants at high risk of cardiovascular disease.

Methods

We conducted a 2-year prospective cohort study (n=6,874) within the framework of the PREDIMED-Plus study. The participants (with overweight/obesity and metabolic syndrome; mean age 64.9 years; 48.5% women) completed a battery of 8 cognitive tests, and a global cognitive function Z-score (GCF) was estimated. At baseline, participants were categorized by diabetes status (no-diabetes, prediabetes, and <5 or ≥5-year diabetes duration), and also by diabetes control. Furthermore, insulin resistance (HOMA-IR) and glycated hemoglobin (HbA1c) levels were measured, and antidiabetic medications were recorded. Linear and logistic regression models, adjusted by potential confounders, were fitted to assess associations between glycemic status and changes in cognitive function.

Results

Prediabetes status was unrelated to cognitive decline. However, compared to participants without diabetes, those with ≥5-year diabetes duration had greater reductions in GCF (β=-0.11 (95%CI -0.16;-0.06)], as well as in processing speed and executive function measurements. Inverse associations were observed between baseline HOMA-IR and changes in GCF [β=-0.0094 (95%CI -0.0164;-0.0023)], but also between HbA1c levels and changes in GCF [β=-0.0085 (95%CI -0.0115, -0.0055)], the Mini-Mental State Examination, and other executive function tests. Poor diabetes control was inversely associated with phonologic fluency. The use of insulin treatment was inversely related to cognitive function as measured by the GCF [β=-0.31 (95%CI -0.44, -0.18)], and other cognitive tests.

Conclusions

Insulin resistance, diabetes status, longer diabetes duration, poor glycemic control, and insulin treatment were associated with worsening cognitive function changes in the short term in a population at high cardiovascular risk.

Clinical Trial Registration

http://www.isrctn.com/ISRCTN89898870, identifier ISRCTN: 89898870.

Type 2 diabetes mellitus in older adults: clinical considerations and management

The past 50 years have seen a growing ageing population with an increasing prevalence of type 2 diabetes mellitus (T2DM); now, nearly half of all individuals with diabetes mellitus are older adults (aged ≥65 years). Older adults with T2DM present particularly difficult challenges. For example, the accentuated heterogeneity of these patients, the potential presence of multiple comorbidities, the increased susceptibility to hypoglycaemia, the increased dependence on care and the effect of frailty all add to the complexity of managing diabetes mellitus in this age group. In this Review, we offer an update on the key pathophysiological mechanisms associated with T2DM in older people. We then evaluate new evidence relating particularly to the effects of frailty and sarcopenia, the clinical difficulties of age-associated comorbidities, and the implications for existing guidelines and therapeutic options. Our conclusions will focus on the effect of T2DM on an ageing society.

Sex differences in risk factors for cognitive decline and dementia, including death as a competing risk, in individuals with diabetes: Results from the ADVANCE trial

AIM

To estimate the associations between risk factors and cognitive decline (CD)/dementia, and the sex differences in these risk factors in individuals with type 2 diabetes, while accounting for the competing risk of death.

MATERIALS AND METHODS

The Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial of 11,140 individuals with type 2 diabetes was used to estimate the odds of CD/dementia using multinomial logistic regression.

RESULTS

During a median 5-year follow-up, 1827 participants (43.2% women) had CD/dementia (1718 with CD only; 21 with dementia only; 88 with CD and dementia), and 929 (31.0% women) died without CD/dementia. Women had lower odds of CD/dementia than men (odds ratio [OR] [95% confidence interval], 0.88 [0.77, 1.00]); older age, higher total cholesterol, HbA1c, waist circumference, waist-to-height ratio, moderately increased albumin-creatinine ratio, stroke/transient ischaemic attack and retinal disease were each associated with greater odds of CD/dementia; higher years at education completion, baseline cognitive function, taller stature and current alcohol use were inversely associated. Higher waist circumference (women-to-men ratio of ORs [ROR], 1.05 [1.00, 1.10] per 5 cm) and presence of anxiety/depression (ROR, 1.28 [1.01, 1.63]) were associated with greater ORs for CD/dementia in women than men.

CONCLUSIONS

Several risk factors were associated with CD/dementia. Higher waist circumference and mental health symptoms were more strongly associated with CD/dementia in women than men. Further studies should examine the mechanisms that underlie these sex differences.

Cognitive performance declines in older adults with type 1 diabetes: results from 32 years of follow-up in the DCCT and EDIC Study

BACKGROUND

With improved treatment, individuals with type 1 diabetes are living longer but there is limited information on the effects of type 1 diabetes on cognitive ability as they become older adults. We followed up individuals with type 1 diabetes to identify independent risk factors for cognitive decline as people age.

METHODS

1051 participants with type 1 diabetes enrolled in the Diabetes Control and Complications Trial (DCCT) and its follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) study. Participants completed cognitive assessments at baseline (median age 27 years) and 2, 5, 18, and 32 years later (median age 59). HbA_1c levels, frequency of severe hypoglycaemia, non-glycemic risk factors such as elevated blood pressure, and microvascular and macrovascular complications were assessed repeatedly. We examined the effects of these on measures of memory and psychomotor and mental efficiency. These studies are registered with clinicaltrials.gov, NCT00360815 (DCCT) and NCT00360893 (EDIC).

FINDINGS

Over 32 years of follow-up, we found substantive declines in memory and psychomotor and mental efficiency. Between 18 and 32 years of follow-up, the decline in psychomotor and mental efficiency was five times larger than the change from baseline to year 18. Independent of the other risk factors and comorbidities, exposure to higher HbA_1c levels, more episodes of severe hypoglycaemia, and elevated systolic blood pressure were associated with greater decrements in psychomotor and mental efficiency that was most notable by year 32 (p<0·0001). The combined effect of the presence of these three risk factors is the equivalent to an additional 9·4 years of age.

INTERPRETATION

Cognitive function declines with ageing in type 1 diabetes. The association of glycaemia and blood pressure levels with cognitive decline suggests that better management might preserve cognitive function.

FUNDING

United States National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Disease.

Association Between Age at Diabetes Onset and Subsequent Risk of Dementia

IMPORTANCE

Trends in type 2 diabetes show an increase in prevalence along with younger age of onset. While vascular complications of early-onset type 2 diabetes are known, the associations with dementia remains unclear.

OBJECTIVE

To determine whether younger age at diabetes onset is more strongly associated with incidence of dementia.

DESIGN, SETTING, AND PARTICIPANTS

Population-based study in the UK, the Whitehall II prospective cohort study, established in 1985-1988, with clinical examinations in 1991-1993, 1997-1999, 2002-2004, 2007-2009, 2012-2013, and 2015-2016, and linkage to electronic health records until March 2019. The date of final follow-up was March 31, 2019.

EXPOSURES

Type 2 diabetes, defined as a fasting blood glucose level greater than or equal to 126 mg/dL at clinical examination, physician-diagnosed type 2 diabetes, use of diabetes medication, or hospital record of diabetes between 1985 and 2019.

MAIN OUTCOMES AND MEASURES

Incident dementia ascertained through linkage to electronic health records.

RESULTS

Among 10 095 participants (67.3% men; aged 35-55 years in 1985-1988), a total of 1710 cases of diabetes and 639 cases of dementia were recorded over a median follow-up of 31.7 years. Dementia rates per 1000 person-years were 8.9 in participants without diabetes at age 70 years, and rates were 10.0 per 1000 person-years for participants with diabetes onset up to 5 years earlier, 13.0 for 6 to 10 years earlier, and 18.3 for more than 10 years earlier. In multivariable-adjusted analyses, compared with participants without diabetes at age 70, the hazard ratio (HR) of dementia in participants with diabetes onset more than 10 years earlier was 2.12 (95% CI, 1.50-3.00), 1.49 (95% CI, 0.95-2.32) for diabetes onset 6 to 10 years earlier, and 1.11 (95% CI, 0.70-1.76) for diabetes onset 5 years earlier or less; linear trend test (P < .001) indicated a graded association between age at onset of type 2 diabetes and dementia. At age 70, every 5-year younger age at onset of type 2 diabetes was significantly associated with an HR of dementia of 1.24 (95% CI, 1.06-1.46) in analyses adjusted for sociodemographic factors, health behaviors, and health-related measures.

CONCLUSIONS AND RELEVANCE

In this longitudinal cohort study with a median follow-up of 31.7 years, younger age at onset of diabetes was significantly associated with higher risk of subsequent dementia.

The Relationship Between Glucose Control and Cognitive Function in People With Diabetes After a Lacunar Stroke

CONTEXT

Lacunar strokes and diabetes are risk factors for cognitive dysfunction. Elucidating modifiable risk factors for cognitive dysfunction has great public health implications. One factor may be glycemic status, as measured by glycated hemoglobin (A1c).

OBJECTIVE

The aim of this study was to assess the relationship between A1c and cognitive function in lacunar stroke patients with diabetes.

METHODS

The effect of baseline and follow-up A1c on the baseline and the change in Cognitive Assessment Screening Instrument (CASI) score over time among participants with a median of 2 cognitive assessments (range, 1-5) was examined in 942 individuals with diabetes and a lacunar stroke who participated in the Secondary Prevention of Small Subcortical Strokes (SPS3) trial (ClinicalTrials.gov No. NCT00059306).

RESULTS

Every 1% higher baseline A1c was associated with a 0.06 lower standardized CASI z score (95% CI, -0.101 to -0.018). Higher baseline A1c values were associated with lower CASI z scores over time (P for interaction = .037). A 1% increase in A1c over time corresponded with a CASI score decrease of 0.021 (95% CI, -0.0043 to -0.038) during follow-up. All these remained statistically significant after adjustment for age, sex, education, race, depression, hypertension, hyperlipidemia, body mass index, cardiovascular disease, obstructive sleep apnea, diabetic retinopathy, nephropathy insulin use, and white-matter abnormalities.

CONCLUSION

This analysis of lacunar stroke patients with diabetes demonstrates a relationship between A1c and change in cognitive scores over time. Intervention studies are needed to delineate whether better glucose control could slow the rate of cognitive decline in this high-risk population.

Cardiovascular risk and midlife cognitive decline in the Study of Women's Health Across the Nation

INTRODUCTION

Cardiovascular risk factors in midlife have been linked to late life risk for Alzheimer's disease and related dementias (ADRD). The relation of vascular risk factors on cognitive decline within midlife has been less studied.

METHODS

Using data from the Study of Women's Health Across the Nation, we examined associations of midlife hypertension, elevated lipid levels, diabetes, fasting glucose, central adiposity, and Framingham heart age with rates of cognitive decline in women who completed multiple cognitive assessments of processing speed, and working and verbal memory during midlife.

RESULTS

Diabetes, elevated fasting glucose, central obesity, and heart age greater than chronological age were associated with rate of decline in processing speed during midlife. Vascular risk factors were not related to rate of decline in working or verbal memory.

DISCUSSION

Midlife may be a critical period for intervening on cardiovascular risk factors to prevent or delay later life cognitive impairment and ADRD.

Trends in predominant causes of death in individuals with and without diabetes in England from 2001 to 2018: an epidemiological analysis of linked primary care records

BACKGROUND

The prevalence of diabetes has increased in the UK and other high-income countries alongside a substantial decline in cardiovascular mortality. Yet data are scarce on how these trends have changed the causes of death in people with diabetes who have traditionally died primarily of vascular causes. We estimated how all-cause mortality and cause-specific mortality in people with diabetes have changed over time, how the composition of the mortality burden has changed, and how this composition compared with that of the non-diabetes population.

METHODS

In this epidemiological analysis of primary care records, we identified 313 907 individuals with diabetes in the Clinical Practice Research Datalink, a well described primary care database, between 2001 to 2018, and linked these data to UK Office for National Statistics mortality data. We assembled serial cross sections with longitudinal follow-up to generate a mixed prevalence and incidence study population of patients with diabetes. We used discretised Poisson regression models to estimate annual death rates for deaths from all causes and 12 specific causes for men and women with diabetes. We also identified age-matched and sex matched (1:1) individuals without diabetes from the same dataset and estimated mortality rates in this group.

FINDINGS

Between Jan 1, 2001, and Oct 31, 2018, total mortality declined by 32% in men and 31% in women with diagnosed diabetes. Death rates declined from 40·7 deaths per 1000 person-years to 27·8 deaths per 1000 person-years in men and from 42·7 deaths per 1000 person-years to 29·5 deaths per 1000 person-years in women with diagnosed diabetes. We found similar declines in individuals without diabetes, hence the gap in mortality between those with and without diabetes was maintained over the study period. Cause-specific death rates declined in ten of the 12 cause groups, with exceptions in dementia and liver disease, which increased in both populations. The large decline in vascular disease death rates led to a transition from vascular causes to cancers as the leading contributor to death rates in individuals with diagnosed diabetes and to the gap in death rates between those with and without diabetes.

INTERPRETATION

The decline in vascular death rates has been accompanied by a diversification of causes in individuals with diagnosed diabetes and a transition from vascular diseases to cancers as the leading contributor to diabetes-related death. Clinical and preventative approaches must reflect this trend to reduce the excess mortality risk in individuals with diabetes.

FUNDING

Wellcome Trust.

No Effects of Acute Psychosocial Stress on Working Memory in Older People With Type 2 Diabetes

Type 2 diabetes (T2D) has been considered a public health threat due to its growing prevalence, particularly in the older population. It is important to know the effects of psychosocial stress and its potential consequences for some basic cognitive processes that are important in daily life. Currently, there is very little information about how people with T2D face acute psychosocial stressors, and even less about how their response affects working memory (WM), which is essential for their functionality and independence. Our aim was to characterize the response to an acute laboratory psychosocial stressor and its effects on WM in older people with T2D. Fifty participants with T2D from 52 to 77 years old were randomly assigned to a stress (12 men and 12 women) or control (12 men and 14 women) condition. Mood and physiological (cortisol, C, and salivary alpha-amylase, sAA) responses to tasks were measured. In addition, participants completed a WM test before and after the stress or control task. Our results showed that the TSST elicited higher negative affect and greater C and sAA responses than the control task. No significant differences in WM were observed depending on the exposure to stress or the control task. Finally, participants who showed higher C and sAA responses to the stressor had lower WM performance. Our results indicate that medically treated older adults with T2D show clear, typical mood and physiological responses to an acute psychosocial stressor. Finally, the lack of acute psychosocial stress effects on WM suggests that it could be related to aging and not to this disease, at least when T2D is adequately treated.

Glucose-Dementia Association Is Consistent Over Blood Pressure/Antihypertensive Groups

BACKGROUND

Higher glucose levels are associated with dementia risk in people with and without diabetes. However, little is known about how this association might vary by hypertension status and antihypertensive treatment. Most studies on modifiable dementia risk factors consider each factor in isolation.

OBJECTIVE

To test the hypothesis that hypertension and antihypertensive treatments may modify associations between glucose levels and dementia.

METHODS

Analyses of data generated from a research study and clinical care of participants from a prospective cohort of dementia-free older adults, including glucose measures, diabetes and antihypertensive treatments, and blood pressure data. We defined groups based on blood pressure (hypertensive versus not, ≥140/90 mmHg versus <140/90 mmHg) and antihypertensive treatment intensity (0, 1, or ≥2 classes of antihypertensives). We used Bayesian joint models to jointly model longitudinal exposure and time to event data.

RESULTS

A total of 3,056 participants without diabetes treatment and 480 with diabetes treatment were included (mean age at baseline, 75.1 years; mean 7.5 years of follow-up). Higher glucose levels were associated with greater dementia risk among people without and with treated diabetes. Hazard ratios for dementia were similar across all blood pressure/antihypertensive treatment groups (omnibus p = 0.82 for people without and p = 0.59 for people with treated diabetes).

CONCLUSION

Hypertension and antihypertensive treatments do not appear to affect the association between glucose and dementia risk in this population-based longitudinal cohort study of community-dwelling older adults. Future studies are needed to examine this question in midlife and by specific antihypertensive treatments.

Obesity-induced cognitive impairment in older adults: a microvascular perspective

Over two-thirds of individuals aged 65 and older are obese or overweight in the United States. Epidemiological data show an association between the degree of adiposity and cognitive dysfunction in the elderly. In this review, the pathophysiological roles of microvascular mechanisms, including impaired endothelial function and neurovascular coupling responses, microvascular rarefaction, and blood-brain barrier disruption in the genesis of cognitive impairment in geriatric obesity are considered. The potential contribution of adipose-derived factors and fundamental cellular and molecular mechanisms of senescence to exacerbated obesity-induced cerebromicrovascular impairment and cognitive decline in aging are discussed.

Increased β-site APP cleaving enzyme 1-mediated insulin receptor cleavage in type 2 diabetes mellitus with cognitive impairment

INTRODUCTION

Patients with type 2 diabetes mellitus (T2DM) are at a high risk of cognitive impairment, with insulin resistance playing a pivotal role. β-site amyloid precursor protein cleaving enzyme 1 (BACE1) is considered a predictor of Alzheimer's disease. However, the potential roles of BACE1 in insulin resistance and the risk of cognitive impairment in T2DM remain unclear.

METHODS

We measured plasma BACE1 levels, BACE1 cleavage activities for Swedish mutant amyloid precursor protein (APPsw) and insulin receptor β subunit (INSR-β), and soluble INSR (sINSR) levels in a clinical cohort study.

RESULTS

T2DM patients with or without cognitive impairment exhibited elevated plasma BACE1 levels and BACE1 enzymatic activities for APPsw and INSR-β, and sINSR levels. Moreover, the glycemic status correlated with elevated BACE1 levels and BACE1-mediated INSR cleavage, which was associated with insulin resistance.

DISCUSSION

The elevated BACE1 levels in T2DM may contribute to increasing the cognitive impairment risk through both amyloidogenesis and insulin resistance.

Exercise and the Risk of Mild Cognitive Impairment: Does the Effect Depend on Vascular Factors?

INTRODUCTION

Although exercise is associated with a lower risk for mild cognitive impairment (MCI), it is unclear whether its protective effect depends on the presence or absence of vascular factors.

METHODS

In an exploratory study of data from a population-based cohort, 1254 participants aged 65+ years were followed for 10 years for incident MCI. The main effect of baseline total minutes of exercise per week (0 vs. 1 to 149 vs. 150+), and its interaction with several vascular factors, on risk for incident MCI was examined using Cox proportional hazards regression models, adjusting for demographics.

RESULTS

Compared with no exercise, 1 to 149 minutes [hazard ratio (HR)=0.90; 95% confidence interval (95% CI), 0.69-1.16] and 150 or more minutes per week (HR=0.84; 95% CI, 0.66-1.07) of exercise lowered risk for incident MCI in a dose-dependent manner. The majority of interactions were not statistically significant, but risk reduction effect sizes of <0.75 suggested that exercise may have stronger effects among those without high cholesterol, never smoking, and not currently consuming alcohol; also, those with arrhythmia, coronary artery disease, and heart failure. Overall, there was a pattern of exercise being associated with lower MCI risk among those without vascular factors.

CONCLUSIONS

Spending more time engaging in exercise each week may offer protection against MCI in late life, with some variation among those with different vascular conditions and risk factors. Our findings may help target subgroups for exercise recommendations and interventions, and also generate hypotheses to test regarding underlying mechanisms.